The 2021 Classification for Output Areas (2021 OAC) is a hierarchical geodemographic classification across the UK which identifies areas of the country with similar characteristics. The OAC is produced as a collaboration between the Office for National Statistics and University College London. The classification contains the following breakdown of Output Areas into 8 different supergroups, into which are nested 21 groups and 52 sub-groups.
Content
The data is available for download at the bottom of this page. Also available for download are a methodological paper, which outlines the approach taken to develop the classification, Local Authority atlases, and pen portraits, which provide additional information about the variables and terms used. Classification geodata can also be downloaded below.
Quality, Representation and Bias
As the Census in Scotland was delayed from 2021 until 2022, and small area outputs from Northern Ireland's Census were not available at the time of production of the classification, this data release covers England and Wales only.
A journal article accompanies 2021 OAC which provides a thorough evaluation. The classification was created using 2021 Census Output Area data for England and Wales; aggregate published 2021 Northern Ireland data, apportioned to 2011 small area census geography; and 2011 Scottish Census results carried forward in adjusted or unadjusted form. However, this classification release with the ONS was constrained only to England and Wales as an interim classification. The full UK OAC as presented in the paper is also available here.
In general terms, a geodemographic classification presents a best effort of the authors to represent the characteristics of the population and geographic context, however, there are decisions made during the classification process that guide these representations. Again for a full overview of these decisions and their rationale, see the published paper.
Version History
- 1.0 - OAC 2001
- 2.0 - OAC 2011
- 3.0 - OAC 2021 (Initial release for England/Wales)
- 3.01 - Addition of index scores by local authority
- 3.02 - Addition of group populations by local authority [this version]
- 3.1 - UK-OAC Modelled (Safeguarded release)
- 3.2 - UK-OAC Actual (Safeguarded release)
